To help his friend, Geoffrey Horner, who has become embroiled with the Chartists, evade murder charges in England, his barrister, Frederick Conyngham, attracts suspicion on himself and leaves for Spain, where he becomes an officer on the Royalist side in the Carlist War. Conyngham becomes immersed in intrigue when what he thinks is a love letter he has agreed to deliver, turns out to be a Carlist manifesto. His adventures take him to Madrid, Toledo, and beyond.

To help his friend, Geoffrey Horner, who has become embroiled with the Chartists, evade murder charges in England, his barrister, Frederick Conyngham, attracts suspicion on himself and leaves for Spain, where he becomes an officer on the Royalist side in the Carlist War. Conyngham becomes immersed in intrigue when what he thinks is a love letter he has agreed to deliver, turns out to be a Carlist manifesto. His adventures take him to Madrid, Toledo, and beyond.